An aircraft in flight generates, in its wake, two wake vortexes. From the wings, the vortexes tend first of all to approach one another, then to maintain a more or less constant distance between one another while losing altitude relative to the altitude at which they were generated.
As is known, the position of the centres and the force of circulation of the vortexes generated by an aircraft can be computed from flight parameters of the aircraft such as the weight, the altitude, the roll angle, the aerodynamic configuration, the wing span, the density of the air at the point of flight, the speed, etc.
It is advantageous for an aircraft, called intruding aircraft, to be able to compute the positions of the centres of the wake vortexes generated by a leading aircraft, in order:                to fly in formation behind the leading aircraft by maximizing the benefit from the up draughts of the vortexes in order to reduce its fuel consumption; or        to avoid undergoing turbulences induced by the vortexes.        